The liquid crystal display device is widely used because it has the advantage of small size, light weight, low power consumption, etc. The liquid crystal display device usually includes a liquid crystal display panel and a back light module, the back light module is used to provide area light source for liquid crystal display panel. The In-Plane Switching (IPS) mode display of the liquid crystal display (also called in-plane switching mode) is a mode of using an electric field component substantially parallel to the substrate to the liquid crystal molecules responding along the in-plane direction of the substrate. Because the IPS liquid crystal display panel has the advantage of viewing angle, is widely used in various display purposes. In the IPS mode of the liquid crystal display panel, a multi-dimensional is formed by a parallel electric field generated by the edge of the pixel electrode or the common electric and a longitudinal electric field generated between the pixel electrode and the common electrode, so that the liquid crystal cell between the pixel electrode or the common electrode, the pixel electrode or the common electrode orientation of the liquid crystal molecules just above all can generate a rotary converter, thereby improving the crystal plane orientation system efficiency, and increasing the light transmission efficiency. However, the array substrate in the conventional IPS liquid crystal display panel is using common electrode (COM) line to provide driving voltage to the common electrode, further, the common electrode line and the gate electrode line are made by the same metal layer. Due to the nature of the metal opaque, reducing the light transmittance of the array substrate, i.e. decreasing the aperture ratio of the array substrate.